\begin{tikzpicture}
    \pgfmathsetmacro{\abc}{30} % 角 ABC 的度数
    \pgfmathsetmacro{\c}{4}

    \tkzDefPoints{0/0/B, \c/0/C, \c/\c/D}
    \tkzDefPointBy[rotation=center B angle \abc](C)  \tkzGetPoint{a}
    \tkzDefPointBy[projection=onto B--a](C)  \tkzGetPoint{A}
    \tkzDrawPolygon[fill=gray!20](A,B,C)

    \tkzDefPointOnLine[pos=.5](B,D)  \tkzGetPoint{O}
    \foreach \n in {90, 180, 270} {
        \tkzDefPointBy[rotation=center O angle \n](A)  \tkzGetPoint{A'}
        \tkzDefPointBy[rotation=center O angle \n](B)  \tkzGetPoint{B'}
        \tkzDefPointBy[rotation=center O angle \n](C)  \tkzGetPoint{C'}
        \tkzDrawPolygon[fill=gray!20](A',B',C')
    }

    \tkzLabelSegment[below left](A,C){$b$}
    \tkzLabelSegment[below right](A,B){$a$}
    \tkzLabelSegment[below](B,C){$c$}
    \tkzLabelSegment[right](C,D){$c$}
\end{tikzpicture}

